Lateral Masking as a Determinant of Global Dominance

Perception ◽  
1992 ◽  
Vol 21 (6) ◽  
pp. 705-716 ◽  
Author(s):  
K Wayne Podrouzek ◽  
Vito Modigliani ◽  
Vincent Di Lollo
Keyword(s):  
Reaction Time ◽  
Compound Stimulus ◽  
High Spatial Frequency ◽  
Indirect Evidence ◽  
Dependent Measure ◽  
Global Precedence ◽  
Lateral Masking ◽  
Compound Images ◽  
Frequency Components ◽  
Inhibitory Interactions

The term compound letter refers to a large (global) letter made up of small (local) letters. Reaction time to identify local letters is longer when local and global letters are different than when they are the same (the global dominance effect). The possible contribution of lateral masking to this effect was investigated. Lateral masking denotes reduced probability of identifying a stimulus when it is closely surrounded by other stimuli (as is the case for the local items in a compound stimulus). Three experiments were conducted in which the dependent measure was percentage of correct responses, rather than reaction time. In experiment 1 compound letters were used; accuracy of performance yielded evidence of global dominance such as obtained with reaction time measures. In experiments 2 and 3 the strength of lateral masking in geometrical forms was varied by varying the density of their component items. In agreement with earlier suggestions based on indirect evidence, the results directly implicated lateral masking as an important determinant of global dominance. However, lateral masking could not account fully for the experimental outcome. Factors beyond lateral masking, such as global precedence in the processing sequence or inhibitory interactions among low and high spatial-frequency components of the compound images are required in order to provide a comprehensive account of global dominance effects.

Cortical processing of second-order motion

1999 ◽  
Vol 16 (3) ◽  
pp. 527-540 ◽  
Author(s):  
ISABELLE MARESCHAL ◽  
CURTIS L. BAKER
Keyword(s):  
Spatial Frequency ◽  
High Spatial Frequency ◽  
Second Order ◽  
Spatial Properties ◽  
Processing Stream ◽  
Spatial Frequencies ◽  
Nonlinear Input ◽  
Nonlinear Processing ◽  
Frequency Components ◽  
Optimal Values

Neurons in the mammalian visual cortex have been found to respond to second-order features which are not defined by changes in luminance over the retina (Albright, 1992; Zhou & Baker, 1993, 1994, 1996; Mareschal & Baker, 1998a,b). The detection of these stimuli is most often accounted for by a separate nonlinear processing stream, acting in parallel to the linear stream in the visual system. Here we examine the two-dimensional spatial properties of these nonlinear neurons in area 18 using envelope stimuli, which consist of a high spatial-frequency carrier whose contrast is modulated by a low spatial-frequency envelope. These stimuli would fail to elicit a response in a conventional linear neuron because they are designed to contain no spatial-frequency components overlapping the neuron's luminance defined passband. We measured neurons' responses to these stimuli as a function of both the relative spatial frequencies and relative orientations of the carrier and envelope. Neurons' responses to envelope stimuli were narrowband to the carrier spatial frequency, with optimal values ranging from 8- to 30-fold higher than the envelope spatial frequencies. Neurons' responses to the envelope stimuli were strongly dependent on the orientation of the envelope and less so on the orientation of the carrier. Although the selectivity to the carrier orientation was broader, neurons' responses were clearly tuned, suggesting that the source of nonlinear input is cortical. There was no fixed relationship between the optimal carrier and envelope spatial frequencies or orientations, such that nonlinear neurons responding to these stimuli could perhaps respond to a variety of stimuli defined by changes in scale or orientation.

scholarly journals The effect of acquisition resolution on orientation decoding from V1 BOLD fMRI at 7 Tesla

2016 ◽  
Author(s):  
Ayan Sengupta ◽  
Renat Yakupov ◽  
Oliver Speck ◽  
Stefan Pollmann ◽  
Michael Hanke
Keyword(s):  
Large Scale ◽  
High Spatial Frequency ◽  
7 Tesla ◽  
Fmri Data ◽  
Response Patterns ◽  
Bold Fmri ◽  
Low Pass ◽  
Frequency Components ◽  
Multivariate Pattern

AbstractA decade after it was shown that the orientation of visual grating stimuli can be decoded from human visual cortex activity by means of multivariate pattern classification of BOLD fMRI data, numerous studies have investigated which aspects of neuronal activity are reflected in BOLD response patterns and are accessible for decoding. However, it remains inconclusive what the effect of acquisition resolution on BOLD fMRI decoding analyses is. The present study is the first to provide empirical ultra high-field fMRI data recorded at four spatial resolutions (0.8 mm, 1.4 mm, 2 mm, and 3 mm isotropic voxel size) on this topic — in order to test hypotheses on the strength and spatial scale of orientation discriminating signals. We present detailed analysis, in line with predictions from previous simulation studies, about how the performance of orientation decoding varies with different acquisition resolutions. Moreover, we also examine different spatial filtering procedures and its effects on orientation decoding. Here we show that higher-resolution scans with subsequent down-sampling or low-pass filtering yield no benefit over scans natively recorded in the corresponding lower resolution regarding decoding accuracy. The orientation-related signal in the BOLD fMRI data is spatially broadband in nature, includes both high spatial frequency components, as well as large-scale biases previously proposed in the literature. Moreover, we found above chance-level contribution from large draining veins to orientation decoding. Acquired raw data were publicly released to facilitate further investigation.

scholarly journals Manipulation of glossiness perception by contrast enhancement of high spatial frequency components

2020 ◽  
Vol 20 (11) ◽  
pp. 364
Author(s):  
Hiroaki Kiyokawa ◽  
Tomonori Tashiro ◽  
Yasuki Yamauchi ◽  
Takehiro Nagai
Keyword(s):  
Spatial Frequency ◽  
Contrast Enhancement ◽  
High Spatial Frequency ◽  
Frequency Components

scholarly journals Evaluating the Potential of Laser Beam Quality Improvement by Adaptive Optics System

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Kai Han ◽  
Wenda Cui ◽  
Yi Yang ◽  
Fengjie Xi ◽  
Xiao Li ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Laser Intensity ◽  
Beam Quality ◽  
Evaluation Criteria ◽  
High Spatial Frequency ◽  
High Energy ◽  
Improvement Potential ◽  
Frequency Components ◽  
Laser Beam Quality ◽  
Adaptive Optics System

AO (adaptive optics) systems have been extensively used to improve the beam quality in high-energy lasers; however, few studies have focused on how much the beam quality could be improved. A novel evaluation criteria and factor is presented in this paper. The factor, defined as power in ring (PIR), is expressed by distinguishing the low- and high-spatial frequency components in the far-field laser intensity distribution. Beams with different PIR values are generated in our model, and then they are compensated by AO systems. Calculation result shows that the PIR factor could evaluate a laser beam’s improvement potential by an AO system quantitatively.

Extrasensory Perception Examined Using a Reaction Time Measure

1987 ◽  
Vol 64 (2) ◽  
pp. 499-502
Author(s):  
Terence M. Hines ◽  
Paul Lang ◽  
Karyn Seroussi
Keyword(s):  
Reaction Time ◽  
Dependent Measure ◽  
Reaction Time Measure ◽  
Reaction Time Paradigm ◽  
Extrasensory Perception

ESP research has depended almost exclusively on measures of accuracy. Such measures are much less sensitive than reaction time measures, which have never been used to evaluate claims for ESP. In this paper we describe the use of a reaction time paradigm in the investigation of ESP. In spite of the greater sensitivity of this dependent measure, no evidence for ESP was found.

scholarly journals EXPRESS: T1 difficulty does not modulate the magnitude of the attentional blink

2021 ◽  
pp. 174702182110547
Author(s):  
Thomas Spalek ◽  
Hayley Lagroix ◽  
Vincent Di Lollo
Keyword(s):  
Reaction Time ◽  
Visual System ◽  
Attentional Blink ◽  
Refractory Period ◽  
Dependent Measure ◽  
Identification Accuracy ◽  
Laboratory Studies ◽  
Response Scale ◽  
Scale Removal ◽  
Rapid Sequence

When the visual system is busy processing one stimulus it has problems processing a subsequent stimulus if it arrives soon after the first. Laboratory studies of this second-stimulus impairment – known as ¬attentional blink (AB) – have employed two targets (T1, T2) presented in rapid sequence, and have found identification accuracy to be nearly perfect for T1 but impaired for T2. It is commonly believed that the magnitude of the AB is related directly to the difficulty of T1: the greater the T1 difficulty, the larger the AB. A survey of the experimental literature disconfirms that belief showing it to have arisen from artificial constraints imposed by the 100% limit of the response scale. Removal of that constraint, either by using reaction time (RT) instead of accuracy as the dependent measure, or in experiments in which the functions of T2 accuracy over lags do not converge to the limit of the response scale, reveals parallel functions for the easy-T1 and the hard-T1 conditions, consistent with the idea that T1 difficulty does not modulate AB magnitude. This finding is problematic for all but the Boost-and-Bounce and the Locus Coeruleus-Norepinephrine theories in which T1 acts merely as a trigger for an eventual refractory period that leads to the failure to process T2, rendering T1 difficulty and its relationship to the AB an irrelevant consideration.

Dynamics of Adaptation to Contrast

Perception ◽  
1982 ◽  
Vol 11 (5) ◽  
pp. 505-528 ◽  
Author(s):  
David Rose ◽  
Ivan Lowe
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Power Function ◽  
Single Phase ◽  
Detection Threshold ◽  
High Spatial Frequency ◽  
Sinusoidal Grating ◽  
Dual Phase ◽  
High Contrast ◽  
Inhibitory Interactions

An investigation has been made into the temporal parameters with which the detection threshold for a sinusoidal grating changes during and after adaptation to the same grating at high contrast. Stationary high-spatial-frequency gratings and a phase-reversing low-spatial-frequency grating have been studied separately. It was found that the threshold continues to rise during adaptation for at least 6 min without sign of levelling off, and that full recovery from 6 min of adaptation can take more than 45 min. Intermittent adaptation and continuous adaptation for the same period produce similar effects. Single-phase and dual-phase exponential fits to the data are rejected, and it is concluded that the level of adaptation of the visual system to spatial contrast changes as a power function of time. However, recovery is not always monotonic, especially after adaptation to phase-reversing gratings. This may be due to inhibitory interactions between channels (in particular, those for pattern and movement information).

scholarly journals Human Performance Deterioration Due to Prolonged Wakefulness Can Be Accurately Detected Using Time-Varying Spectral Analysis of Electrodermal Activity

2018 ◽  
Vol 60 (7) ◽  
pp. 1035-1047 ◽  
Author(s):  
Hugo F. Posada-Quintero ◽  
Jeffrey B. Bolkhovsky ◽  
Michael Qin ◽  
Ki H. Chon
Keyword(s):  
Nervous System ◽  
Autonomic Nervous System ◽  
Reaction Time ◽  
Sleep Deprivation ◽  
Skin Conductance ◽  
High Frequency ◽  
Human Performance ◽  
Electrodermal Activity ◽  
Time Varying ◽  
Frequency Components

Objective: The aim was to determine if indices of the autonomic nervous system (ANS), derived from the electrodermal activity (EDA) and electrocardiogram (ECG), could be used to detect deterioration in human cognitive performance on healthy participants during 24-hour sleep deprivation. Background: The ANS is highly sensitive to sleep deprivation. Methods: Twenty-five participants performed a desktop-computer-based version of the psychomotor vigilance task (PVT) every 2 hours. Simultaneously with reaction time (RT) and false starts from PVT, we measured EDA and ECG. We derived heart rate variability (HRV) measures from ECG recordings to assess dynamics of the ANS. Based on RT values, average reaction time (avRT), minor lapses (RT > 500 ms), and major lapses (RT > 1 s) were computed as indices of performance, along with the total number of false starts. Results: Performance measurement results were consistent with the literature. The skin conductance level, the power spectral index, and the high-frequency components of HRV were not significantly correlated to the indices of performance. The nonspecific skin conductance responses, the time-varying index of EDA (TVSymp), and normalized low-frequency components of HRV were significantly correlated to indices of performance ( p < 0.05). TVSymp exhibited the highest correlation to avRT (–0.92), major lapses (–0.85), and minor lapses (–0.83). Conclusion: We conclude that indices that account for high-frequency dynamics in the EDA, specifically the time-varying approach, constitute a valuable tool for understanding the changes in the autonomic nervous system. Application: This can be used to detect the adverse effects of prolonged wakefulness on human performance.

scholarly journals Effects of Spatial Frequency Filtering Choices on the Perception of Filtered Images

Vision ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 29
Author(s):  
Sabrina Perfetto ◽  
John Wilder ◽  
Dirk B. Walther
Keyword(s):  
Spatial Frequency ◽  
Behavioral Outcomes ◽  
High Spatial Frequency ◽  
Frequency Content ◽  
Frequency Filtering ◽  
Image Content ◽  
Specific Choice ◽  
Spatial Frequencies ◽  
Spatial Frequency Filtering ◽  
Frequency Components

The early visual system is composed of spatial frequency-tuned channels that break an image into its individual frequency components. Therefore, researchers commonly filter images for spatial frequencies to arrive at conclusions about the differential importance of high versus and low spatial frequency image content. Here, we show how simple decisions about the filtering of the images, and how they are displayed on the screen, can result in drastically different behavioral outcomes. We show that jointly normalizing the contrast of the stimuli is critical in order to draw accurate conclusions about the influence of the different spatial frequencies, as images of the real world naturally have higher contrast energy at low than high spatial frequencies. Furthermore, the specific choice of filter shape can result in contradictory results about whether high or low spatial frequencies are more useful for understanding image content. Finally, we show that the manner in which the high spatial frequency content is displayed on the screen influences how recognizable an image is. Previous findings that make claims about the visual system’s use of certain spatial frequency bands should be revisited, especially if their methods sections do not make clear what filtering choices were made.

Sign in / Sign up

Export Citation Format

Share Document